1. Technical Field
The techniques described herein relate to control circuits and methods for a synchronous rectifier.
2. Discussion of the Related Art
A synchronous rectifier is a rectifier implemented by transistors rather than diodes. A control circuit controls the timing of switching the transistors based on the received AC waveform to mimic the switching on and off of the diodes in a conventional rectifier. Synchronous rectifiers can have improved efficiency over rectifiers implemented by diodes due to the lower voltage drop across them during conduction.
Wireless Power Transfer Systems (WPTS) are gaining increasing popularity as a convenient way to deliver power without wires or connectors. WPTS currently under development in the industry can be separated into two major classes: magnetic induction systems and magnetic resonance (MR) systems. Both types of systems include a wireless power transmitter and a wireless power receiver. Such systems can be used to power or charge mobile battery-powered devices such as smartphones, or tablet computers, for example, among other applications.
Inductive WPTS typically operate in an allocated frequency range of several hundred kilohertz using frequency variation as a power control mechanism. MR WPTS typically operate on a single frequency using input voltage regulation to control output power. In typical applications, MR WPTS operate at a frequency of 6.78 MHz.
Several industry committees such as the Wireless Power Consortium (WPC), the Alliance for Wireless Power/Power Matters Alliance (A4WP/PMA) are working on developing international standards for consumer products based on wireless power transfer.